1. Field of the Invention
The present invention relates to a film forming method for forming a metal film on a surface of a substrate by making a reactive gas into plasma under atmospheric pressure or under a pressure in the vicinity of atmospheric pressure, and to a substrate having a metal film formed by the above-described film forming method.
2. Description of Related Art
In earlier technology, as methods for forming a metal film, which is used as an electrode or the like, on a substrate, there are wet plating methods, such as electroplating, nonelectrolytic plating and the like, dry (vapor) plating methods, such as vacuum deposition, sputtering, ion plating, MOCVD (Metal organic chemical vapor deposition) and the like, plasma spraying, and the like.
However, with respect to the wet plating methods, the kinds of metals which are capable of being plated are limited. Further, troublesome wastewater treatment is required with plating operation. Further, with respect to the dry plating methods, since huge facilities to make a vacuum state are generally required, cost is high, and moreover, there is a problem that the film forming rate is slow. With respect to the plasma spraying method, there is a problem that a precise film is hard to be formed since it is a method for utilizing arc discharge.
Further, recently, an atmospheric pressure plasma method for forming a film by plasma CVD under a pressure in the vicinity of atmospheric pressure has been known. According to this method, the film forming rate is larger than the vacuum state. However, in order to form a pure metal film by the previous atmospheric pressure plasma method, there is a problem that it is inferior in respect of purity and its electric conductivity is low compared with, for example, a vacuum sputtering method or the like.